Motor-driven surgical cutting instrument

ABSTRACT

A motor-driven surgical cutting and fastening instrument that comprises an end effector, an electric motor, and a motor control circuit. The motor control circuit is for monitoring a parameter of the electric motor that is indicative of movement of a moveable member of the end effector, and for adjustably controlling the electric motor based on the monitored parameter to thereby adjustably control movement of the moveable member of the end effector during forward rotation of the electric motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application claiming priority under35 U.S.C. § 120 to U.S. patent application Ser. No. 16/146,065, entitledMOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, filed Sep. 28, 2018, whichissued on Jan. 26, 2021 as U.S. Pat. No. 10,898,184, which is acontinuation application claiming priority under 35 U.S.C. § 120 to U.S.patent application Ser. No. 14/847,831, entitled MOTOR-DRIVEN SURGICALCUTTING INSTRUMENT, filed Sep. 8, 2015, which issued on Aug. 11, 2020 asU.S. Pat. No. 10,736,628, which is a continuation application claimingpriority under 35 U.S.C. § 120 to U.S. patent application Ser. No.13/784,957, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, filedMar. 5, 2013, which issued on Jan. 24, 2017 as U.S. Pat. No. 9,549,732,which is a continuation application claiming priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 13/486,175, entitledMOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, filed on Jun. 1, 2012, whichissued on Dec. 10, 2013 as U.S. Pat. No. 8,602,287, which is acontinuation application claiming priority under 35 U.S.C. § 120 to U.S.application Ser. No. 12/235,782, entitled MOTOR-DRIVEN SURGICAL CUTTINGINSTRUMENT, filed Sep. 23, 2008, which issued on Jul. 3, 2012 as U.S.Pat. No. 8,210,411, the entire disclosures of which are herebyincorporated by reference herein.

BACKGROUND

Surgical staplers are used to simultaneously make a longitudinalincision in tissue and apply lines of staples on opposing sides of theincision. Such instruments commonly include an end effector having apair of cooperating jaw members that, if the instrument is intended forendoscopic or laparoscopic applications, are capable of passing througha cannula passageway. One of the jaw members receives a staple cartridgehaving at least two laterally spaced rows of staples—one on each side ofthe knife channel. The other jaw member defines an anvil havingstaple-forming pockets aligned with the rows of staples in thecartridge. The instrument includes a plurality of reciprocating wedgesthat, when driven distally, pass through openings in the staplecartridge and engage drivers supporting the staples to effect the firingof the staples toward the anvil. Simultaneously, a cutting instrument(or knife) is drawn distally along the jaw member so that the clampedtissue is cut and fastened (e.g., stapled) at the same time.

An example of a surgical stapler suitable for endoscopic applications isdescribed in U.S. Patent Application Publication No. 2004/0232196,entitled, SURGICAL STAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSINGAND FIRING SYSTEMS, now U.S. Pat. No. 7,000,818, the disclosure of whichis herein incorporated by reference in its entirety. In use, a clinicianis able to close the jaw members of the stapler upon tissue to positionthe tissue prior to firing. Once the clinician has determined that thejaw members are properly gripping tissue, the clinician can then firethe surgical stapler, thereby severing and stapling the tissue. Thesimultaneous severing and stapling actions avoid complications that mayarise when performing such actions sequentially with different surgicaltools that respectively only sever or staple.

Motor-driven endocutters are known in the art. In such devices, a motorpowers the cutting and fastening action of the instrument. It is alsoknown to use an on-board battery, located in the handle of theinstrument, to power the motor. U.S. Patent Application Publication No.2007/0175952, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENINGINSTRUMENT WITH LOADING FORCE FEEDBACK, now U.S. Pat. No. 7,416,101, thedisclosure of which is herein incorporated by reference in its entirety,describes one such motor-driven surgical instrument.

SUMMARY

In one general aspect, the present invention is directed to amotor-driven surgical cutting and fastening instrument. According tovarious embodiments, the instrument may comprise an end effector, ashaft connected to the end effector, and handle connected to the shaft.The end effector may comprise a cutting instrument that, when actuated,longitudinally traverses the end effector to cut tissue clamped in theend effector. The handle may comprise an electric motor for actuatingthe cutting instrument and a motor control circuit for controlling themotor. The motor control circuit may comprise a power source connectedto the motor for electrically powering the motor and a current controlcircuit, connected to the power source, for varying the current suppliedto the motor from the power source. The current control circuit may varythe current supplied to the motor, and consequently, the output torquesupplied by the motor, such that the motor has at least (i) a first, lowpower operational mode for a first portion of a cutting stroke cycle ofthe cutting instrument, and (ii) a second, high power operational modefor a second portion the cutting stroke cycle of the cutting instrument.

That way, for example, according to various embodiments, the motor canstart out at a low power mode at the beginning of the cutting stroke toprovide a soft start quality. After the initial soft start, the motorcan ramp up to full power for the majority of the cutting stroke, butthen transition to a lower power mode before and shortly after thecutting reverses direction. In addition, the motor may transition from ahigh power mode to a low power mode before the cutting instrumentreaches its final, or home, position when it is being retracted.According circuit configurations for controlling the current supplied tothe motor are provided.

In addition, according to various embodiments, the motor control circuitmay actively brake the motor before it reverses direction. For example,the motor control circuit may remove power supplied to the motor justprior to the point in time when the cutting instrument is to reach itsend-of-stroke position and the motor reverses direction. In variousembodiments, the motor control circuit may comprise a memory that storesdata regarding the cartridge loaded in the end effector, from which datathe motor control circuit can determine when in the cutting stroke themotor should be actively braked. In other embodiments, the motor controlcircuit may not include any integrated circuits. In such embodiments, aninterface between the end effector and the cartridge may complete anelectrical circuit that is connected to the motor control circuit andthat has characteristics (e.g., resistance) that control when the motoris actively braked by the motor control circuit.

In various embodiments, a surgical system comprising an end effector, afiring member, a motor, a battery pack, and a control circuit isdisclosed. The end effector comprises a first jaw and a second jawrotatable relative to the first jaw between an open position and aclosed position. The firing member is movable within the end effectoralong a firing path between a starting position and an ending position.The motor comprises a shaft. The motor is configured to drive the firingmember toward the ending position based on the shaft rotating in a firstrotational direction. The battery pack is operably coupled with themotor. The battery pack comprises at least two battery cells. The atleast two battery cells are connected in series as the firing membermoves between the starting position and the ending position. The batterypack is configured a provide a set voltage to the motor during theoperation thereof. The control circuit is operably coupled to the motor.The control circuit is configured to switch between a plurality ofoperational modes during the rotation of the shaft in the firstrotational direction. The plurality of operational modes comprises afirst operational mode in which a first amount of current is supplied tothe motor from the battery pack. The control circuit operates in thefirst operational mode as the firing member is driven from the startingposition toward a predetermined position along the firing path. Theplurality of operational modes further comprises a second operationalmode in which a second amount of current is supplied to the motor fromthe battery pack. The second amount of current is greater than the firstamount of current. The control circuit operates in the secondoperational mode as the firing member is driven from the predeterminedposition toward the ending position. The control circuit comprises apower control switch configurable between a first state and a secondstate. The control circuit is in the first operational mode based on thepower control switch being in the first state. The control circuit is inthe second operational mode based on the power control switch being inthe second state. The surgical system further comprises a positionsensor configured to sense a position of the firing member. The powercontrol switch is configured to transition towards the second statebased on the position sensor sensing the firing member reaching thepredetermined position.

In various embodiments, a surgical system comprising an end effector, afiring member, a motor, a battery pack, and a control circuit isdisclosed. The end effector comprises a first jaw and a second jawrotatable relative to the first jaw between an open position and aclosed position. The firing member is movable within the end effectoralong a firing path between a starting position and an ending position.The motor comprises a shaft. The motor is configured to drive the firingmember toward the ending position based on the shaft rotating in a firstrotational direction. The battery pack is operably coupled with themotor. The battery pack comprises at least two battery cells. The atleast two battery cells are connected in series as the firing membermoves between the starting position and the ending position. The batterypack is configured a provide a set voltage to the motor during theoperation thereof. The control circuit is operably coupled to the motor.The control circuit is configured to switch between a plurality ofoperational modes during the rotation of the shaft in the firstrotational direction. The plurality of operational modes comprises afirst operational mode in which a first amount of current is supplied tothe motor from the battery pack. The control circuit operates in thefirst operational mode as the firing member is driven from the startingposition toward a predetermined position along the firing path. Theplurality of operational modes further comprises a second operationalmode in which a second amount of current is supplied to the motor fromthe battery pack. The second amount of current is greater than the firstamount of current. The control circuit operates in the secondoperational mode as the firing member is driven from the predeterminedposition toward the ending position. The control circuit comprises apower control switch configurable between a first state and a secondstate. The control circuit is in the first operational mode based on thepower control switch being in the first state. The control circuit is inthe second operational mode based on the power control switch being inthe second state. The control circuit further comprises a resistor.Current from the battery pack is configured to flow through the resistorbased on the power control switch being in the first state. Current fromthe battery pack bypasses the resistor based on the power control switchbeing in the second state.

In various embodiments, a surgical system comprising an end effector, afiring member, a motorized system, a power pack, and a control circuitis disclosed. The end effector comprises a first jaw and a second jawmovable relative to the first jaw between an open position and a clampedposition. The firing member is movable within the end effector along afiring path between a proximal position and a distal position. Themotorized system is configured to drive the firing member between theproximal position and the distal position. The power pack is operablycoupled with the motorized system. The power pack comprises at least twopower cells. The at least two power cells are connected in series as thefiring member moves between the proximal position and the distalposition. The power pack is configured to provide a substantiallyconstant voltage to the motorized system during the operation thereof.The control circuit is operably coupled to the motorized system. Thecontrol circuit is configured to switch between a plurality ofoperational configurations as the motorized system drives the firingmember toward the distal position. The plurality of operationalconfigurations comprises a first operational configuration in which afirst amount of current is supplied to the motorized system from thepower pack. The control circuit is in the first operationalconfiguration as the firing member is driven from the proximal positiontoward a predetermined position along the firing path. The plurality ofoperational configurations further comprises a second operationalconfiguration in which a second amount of current is supplied to themotorized system from the power pack. The second amount of current isgreater than the first amount of current. The control circuit is in thesecond operational configuration as the firing member is driven from thepredetermined position toward the distal position. The control circuitcomprises a power control switch configurable between a first state anda second state. The control circuit is in the first operationalconfiguration based on the power control switch being in the firststate. The control circuit is in the second operational configurationbased on the power control switch being in the second state. Thesurgical system further comprises a position sensor configured to sensea position of the firing member. The power control switch is configuredto transition towards the second state based on the position sensorsensing the firing member reaching the predetermined position.

In various embodiments, a surgical system comprising an end effector, afiring member, a motorized system, a power pack, and a control circuitis disclosed. The end effector comprises a first jaw and a second jawmovable relative to the first jaw between an open position and a clampedposition. The firing member is movable within the end effector along afiring path between a proximal position and a distal position. Themotorized system is configured to drive the firing member between theproximal position and the distal position. The power pack is operablycoupled with the motorized system. The power pack comprises at least twopower cells. The at least two power cells are connected in series as thefiring member moves between the proximal position and the distalposition. The power pack is configured to provide a substantiallyconstant voltage to the motorized system during the operation thereof.The control circuit is operably coupled to the motorized system. Thecontrol circuit is configured to switch between a plurality ofoperational configurations as the motorized system drives the firingmember toward the distal position. The plurality of operationalconfigurations comprises a first operational configuration in which afirst amount of current is supplied to the motorized system from thepower pack. The control circuit is in the first operationalconfiguration as the firing member is driven from the proximal positiontoward a predetermined position along the firing path. The plurality ofoperational configurations further comprises a second operationalconfiguration in which a second amount of current is supplied to themotorized system from the power pack. The second amount of current isgreater than the first amount of current. The control circuit is in thesecond operational configuration as the firing member is driven from thepredetermined position toward the distal position. The control circuitcomprises a power control switch configurable between a first state anda second state. The control circuit is in the first operationalconfiguration based on the power control switch being in the firststate. The control circuit is in the second operational configurationbased on the power control switch being in the second state. The controlcircuit further comprises a resistor. Current from the power pack isconfigured to flow through the resistor based on the power controlswitch being in the first state. Current from the power pack bypassesthe resistor based on the power control switch being in the secondstate.

In various embodiments, a surgical system comprising an end effector, afiring member, a motor, a battery pack, and a control circuit isdisclosed. The end effector comprises an anvil and an elongate channel.The anvil and the elongate channel are configurable between an openconfiguration and a closed configuration. The firing member is movablewithin the end effector along a firing path between a starting positionand an ending position. The motor is configured to drive the firingmember toward the ending position. The battery pack is operably coupledwith the motor. The battery pack comprises at least two battery cells.The at least two battery cells are connected in series as the firingmember moves between the starting position and the ending position. Thecontrol circuit is operably coupled to the motor. The control circuit isconfigured to switch between a plurality of operational states as themotor drives the firing member toward the ending position. The pluralityof operational states comprises a first operational state in which afirst amount of current is supplied to the motor from the battery pack.The control circuit operates in the first operational state as thefiring member is driven from the starting position toward apredetermined position along the firing path. The plurality ofoperational states further comprises a second operational state in whicha second amount of current is supplied to the motor from the batterypack. The second amount of current is greater than the first amount ofcurrent. The control circuit operates in the second operational state asthe firing member is driven from the predetermined position toward theending position. A voltage provided to the motor from the battery packis substantially the same in the first operational state and the secondoperational state.

In various embodiments, a surgical system comprising an end effector, afiring member, a motor, a battery pack, and a control circuit isdisclosed. The end effector comprises an anvil and an elongate channel.The anvil and the elongate channel are configurable between an openconfiguration and a closed configuration. The firing member is movablewithin the end effector along a firing path between a starting positionand an ending position. The motor is configured to drive the firingmember toward the ending position. The battery pack is operably coupledwith the motor. The battery pack comprises at least two battery cells.The at least two battery cells are connected in series as the firingmember moves between the starting position and the ending position. Thecontrol circuit is operably coupled to the motor. The control circuit isconfigured to switch between a plurality of operational states as themotor drives the firing member toward the ending position. The pluralityof operational states comprises a first operational state in which afirst amount of current is supplied to the motor from the battery pack.The control circuit operates in the first operational state as thefiring member is driven from the starting position toward apredetermined position along the firing path. The plurality ofoperational states further comprises a second operational state in whicha second amount of current is supplied to the motor from the batterypack. The second amount of current is greater than the first amount ofcurrent. The control circuit operates in the second operational state asthe firing member is driven from the predetermined position toward theending position. A voltage supplied to the motor from the battery packin the second operational state comprises an unadjusted voltage relativeto a voltage supplied to the motor from the battery pack in the firstoperation state.

These and other benefits of the present invention will be apparent fromthe description below.

FIGURES

Various embodiments of the present invention are described herein by wayof example in conjunction with the following figures, wherein:

FIGS. 1, 2, and 24 depict a surgical instrument with an articulatableend effector according to various embodiments of the present invention;

FIGS. 3-5 are exploded views of an end effector and shaft of theinstrument according to various embodiments of the present invention;

FIG. 6 is a side view of the end effector according to variousembodiments of the present invention;

FIG. 7 is an exploded view of the handle of the instrument according tovarious embodiments of the present invention;

FIGS. 8 and 9 are partial perspective views of the handle according tovarious embodiments of the present invention;

FIG. 10 is a side view of the handle according to various embodiments ofthe present invention;

FIGS. 11, 13-18, and 25 are diagrams of motor control circuit accordingto various embodiments of the present invention;

FIGS. 12 and 19 are timing diagrams illustrating operation of theinstrument according to various embodiments of the present invention;

FIGS. 20 and 23 are diagrams of the end effector, without a cartridge,according to various embodiments of the present invention; and

FIGS. 21-22 are diagrams of a replaceable cartridge according to variousembodiments of the present invention.

DESCRIPTION

FIGS. 1 and 2 depict a motor-driven surgical cutting and fasteninginstrument 10 according to various embodiments of the present invention.The illustrated embodiment is an endoscopic instrument and, in general,the embodiments of the instrument 10 described herein are endoscopicsurgical cutting and fastening instruments. It should be noted, however,that the invention is not so limited and that according to otherembodiments of the present invention, the instrument may be anon-endoscopic surgical cutting and fastening instrument, such as alaparoscopic instrument.

The surgical instrument 10 depicted in FIGS. 1 and 2 comprises a handle6, a shaft 8, and an articulating end effector 12 pivotally connected tothe shaft 8 at an articulation pivot 14. An articulation control 16 maybe provided adjacent to the handle 6 to effect rotation of the endeffector 12 about the articulation pivot 14. In the illustratedembodiment, the end effector 12 is configured to act as an endocutterfor clamping, severing and stapling tissue, although, in otherembodiments, different types of end effectors may be used, such as endeffectors for other types of surgical devices, such as graspers,cutters, staplers, clip appliers, access devices, drug/gene therapydevices, ultrasound, RF or laser devices, etc. More details regarding RFdevices may be found in U.S. Pat. No. 5,403,312 and commonly assignedU.S. patent application Ser. No. 12/031,573, entitled SURGICAL CUTTINGAND FASTENING INSTRUMENT HAVING RF ELECTRODES, filed Feb. 14, 2008, bothof which are incorporated by reference in their entirety.

The handle 6 of the instrument 10 may include a closure trigger 18 and afiring trigger 20 for actuating the end effector 12. It will beappreciated that instruments having end effectors directed to differentsurgical tasks may have different numbers or types of triggers or othersuitable controls for operating the end effector 12. The end effector 12is shown separated from the handle 6 by a preferably elongate shaft 8.In one embodiment, a clinician or operator of the instrument 10 mayarticulate the end effector 12 relative to the shaft 8 by utilizing thearticulation control 16, as described in more detail in U.S. PatentApplication Publication No. 2007/0158385, entitled SURGICAL INSTRUMENTHAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No. 7,670,334, whichis incorporated herein by reference in its entirety.

The end effector 12 includes in this example, among other things, astaple channel 22 and a pivotally translatable clamping member, such asan anvil 24, which are maintained at a spacing that assures, when theanvil 24 is in its clamped position, effective stapling and severing oftissue clamped in the end effector 12. The handle 6 includes adownwardly extending pistol grip 26 towards which a closure trigger 18is pivotally drawn by the clinician to cause clamping or closing of theanvil 24 toward the staple channel 22 of the end effector 12 to therebyclamp tissue positioned between the anvil 24 and channel 22. The firingtrigger 20 is farther outboard of the closure trigger 18. Once theclosure trigger 18 is locked in the closure position as furtherdescribed below, the firing trigger 20 may rotate slightly toward thepistol grip 26 so that it can be reached by the operator using one hand.Then the operator may pivotally draw the firing trigger 20 toward thepistol grip 12 to cause the stapling and severing of clamped tissue inthe end effector 12. In other embodiments, different types of clampingmembers besides the anvil 24 could be used.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping the handle 6 of aninstrument 10. Thus, the end effector 12 is distal with respect to themore proximal handle 6. It will be further appreciated that, forconvenience and clarity, spatial terms such as “vertical” and“horizontal” are used herein with respect to the drawings. However,surgical instruments are used in many orientations and positions, andthese terms are not intended to be limiting and absolute.

In operational use, the closure trigger 18 may be actuated first. Oncethe clinician is satisfied with the positioning of the end effector 12,the clinician may draw back the closure trigger 18 to its fully closed,locked position proximate to the pistol grip 26. The firing trigger 20may then be actuated. The firing trigger 20 returns to the open position(shown in FIGS. 1 and 2 ) when the clinician removes pressure, asdescribed more fully below. A release button on the handle 6, whendepressed may release the locked closure trigger 18. The release buttonmay be implemented in various forms such as, for example, as disclosedin U.S. Patent Application Publication No. 2007/0175955, entitledSURGICAL CUTTING AND FASTENING INSTRUMENT WITH CLOSURE TRIGGER LOCKINGMECHANISM, which is incorporated herein by reference in its entirety.

FIG. 3 is an exploded view of the end effector 12 according to variousembodiments. As shown in the illustrated embodiment, the end effector 12may include, in addition to the previously mentioned channel 22 andanvil 24, a cutting instrument 32, a sled 33, a staple cartridge 34 thatis removably seated in the channel 22, and a helical screw shaft 36. Thecutting instrument 32 may be, for example, a knife. The anvil 24 may bepivotably opened and closed at a pivot point 25 connected to theproximate end of the channel 22 between open and closed positions,respectively. The anvil 24 may also include a tab 27 at its proximateend that is inserted into a component of the mechanical closure system(described further below) to open and close the anvil 24. When theclosure trigger 18 is actuated, that is, drawn in by a user of theinstrument 10 toward the pistol grip portion 26, the anvil 24 may pivotabout the pivot point 25 into the clamped or closed position. Ifclamping of the end effector 12 is satisfactory, the operator mayactuate the firing trigger 20, which causes the knife 32 and sled 33 totravel longitudinally along the channel 22, thereby cutting tissueclamped within the end effector 12. The movement of the sled 33 alongthe channel 22 causes the staples of the staple cartridge 34 to bedriven through the severed tissue and against the closed anvil 24, whichturns the staples to fasten the severed tissue. In various embodiments,the sled 33 may be an integral component of the cartridge 34. U.S. Pat.No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING ANE-BEAM FIRING MECHANISM, which is incorporated herein by reference inits entirety, provides more details about such two-stroke cutting andfastening instruments. In various embodiments, the sled 33 may be partof the cartridge 34, such that when the knife 32 retracts following thecutting operation, the sled 33 does not retract.

It should be noted that although the embodiments of the instrument 10described herein employ an end effector 12 that staples the severedtissue, in other embodiments different techniques for fastening orsealing the severed tissue may be used. For example, end effectors thatuse RF energy or adhesives to fasten the severed tissue may also beused. U.S. Pat. No. 5,709,680 entitled ELECTROSURGICAL HEMOSTATICDEVICE, and U.S. Pat. No. 5,688,270 entitled ELECTROSURGICAL HEMOSTATICDEVICE WITH RECESSED AND/OR OFFSET ELECTRODES, which are incorporatedherein by reference in their entirety, disclose an endoscopic cuttinginstrument that uses RF energy to seal the severed tissue. U.S. PatentApplication Publication No. 2007/0102453, now U.S. Pat. No. 7,673,783and U.S. Patent Application Publication No. 2007/0102452, now U.S. Pat.No. 7,607,557, which are also incorporated herein by reference, discloseendoscopic cutting instruments that use adhesives to fasten the severedtissue. Accordingly, although the description herein refers tocutting/stapling operations and the like below, it should be recognizedthat this is an exemplary embodiment and is not meant to be limiting.Other tissue-fastening techniques may also be used.

FIGS. 4 and 5 are exploded views and FIG. 6 is a side view of the endeffector 12 and shaft 8 according to various embodiments. As shown inthe illustrated embodiment, the shaft 8 may include a proximate closuretube 40 and a distal closure tube 42 pivotably linked by a pivot links44. The distal closure tube 42 includes an opening 45 into which the tab27 on the anvil 24 is inserted in order to open and close the anvil 24,as further described below. Disposed inside the closure tubes 40, 42 maybe a proximate spine tube 46. Disposed inside the proximate spine tube46 may be a main rotational (or proximate) drive shaft 48 thatcommunicates with a secondary (or distal) drive shaft 50 via a bevelgear assembly 52. The secondary drive shaft 50 is connected to a drivegear 54 that engages a proximate drive gear 56 of the helical screwshaft 36. The vertical bevel gear 52 b may sit and pivot in an opening57 in the distal end of the proximate spine tube 46. A distal spine tube58 may be used to enclose the secondary drive shaft 50 and the drivegears 54, 56. Collectively, the main drive shaft 48, the secondary driveshaft 50, and the articulation assembly (e.g., the bevel gear assembly52 a-c) are sometimes referred to herein as the “main drive shaftassembly.”

A bearing 38, positioned at a distal end of the staple channel 22,receives the helical drive screw 36, allowing the helical drive screw 36to freely rotate with respect to the channel 22. The helical screw shaft36 may interface a threaded opening (not shown) of the knife 32 suchthat rotation of the shaft 36 causes the knife 32 to translate distallyor proximately (depending on the direction of the rotation) through thestaple channel 22. Accordingly, when the main drive shaft 48 is causedto rotate by actuation of the firing trigger 20 (as explained in moredetail below), the bevel gear assembly 52 a-c causes the secondary driveshaft 50 to rotate, which in turn, because of the engagement of thedrive gears 54, 56, causes the helical screw shaft 36 to rotate, whichcauses the knife driving member 32 to travel longitudinally along thechannel 22 to cut any tissue clamped within the end effector. The sled33 may be made of, for example, plastic, and may have a sloped distalsurface. As the sled 33 traverses the channel 22, the sloped forwardsurface may push up or drive the staples in the staple cartridge throughthe clamped tissue and against the anvil 24. The anvil 24 turns thestaples, thereby stapling the severed tissue. When the knife 32 isretracted, the knife 32 and sled 33 may become disengaged, therebyleaving the sled 33 at the distal end of the channel 22.

In addition, according to various embodiments, the instrument 10 maycomprise a cutting instrument position sensor 150 that senses theposition of the cutting instrument 32 within the staple channel 22. Inone embodiment, the cutting instrument position sensor 150 may comprisesan encoder positioned to sense rotation of the helical screw shaft 36,or any other drive shaft or gear whose rotation is related to theposition of the knife 32 in the end effector 12. Because the rotation ofthe shaft 36 or other drive shafts/gears is proportional to the movementof the cutting instrument 32 along the length of the channel 22, thesignal generated by the encoder 150 is also proportional to the movementof the cutting instrument 32 in the channel 22.

FIGS. 7-10 illustrate an exemplary embodiment of a motor-drivenendocutter. The illustrated embodiment provides user-feedback regardingthe deployment and loading force of the cutting instrument in the endeffector. In addition, the embodiment may use power provided by the userin retracting the firing trigger 20 to power the device (a so-called“power assist” mode). As shown in the illustrated embodiment, the handle6 includes exterior lower sidepieces 59, 60 and exterior upper sidepieces 61, 62 that fit together to form, in general, the exterior of thehandle 6. A battery (or “power source” or “power pack”) 64, such as a Liion battery, may be provided in the pistol grip portion 26 of the handle6. The battery 64 powers an electric motor 65 disposed in an upperportion of the pistol grip portion 26 of the handle 6. According tovarious embodiments, a number of battery cells connected in series maybe used to power the motor 65. In addition, the power source 64 may bereplaceable and/or rechargeable.

The motor 65 may be a DC brushed driving motor having a maximum rotationof, approximately, 25,000 RPM. In other embodiments, the motor 65 mayinclude a brushless motor, a cordless motor, a synchronous motor, astepper motor, or any other suitable electric motor. The motor 64 maydrive a 90° bevel gear assembly 66 comprising a first bevel gear 68 anda second bevel gear 70. The bevel gear assembly 66 may drive a planetarygear assembly 72. The planetary gear assembly 72 may include a piniongear 74 connected to a drive shaft 76. The pinion gear 74 may drive amating ring gear 78 that drives a helical gear drum 80 via a drive shaft82. A ring 84 may be threaded on the helical gear drum 80. Thus, whenthe motor 65 rotates, the ring 84 is caused to travel along the helicalgear drum 80 by means of the interposed bevel gear assembly 66,planetary gear assembly 72, and ring gear 78.

The handle 6 may also include a run motor sensor 110 in communicationwith the firing trigger 20 to detect when the firing trigger 20 has beendrawn in (or “closed”) toward the pistol grip portion 26 of the handle 6by the operator to thereby actuate the cutting/stapling operation by theend effector 12. The sensor 110 may be a proportional sensor such as,for example, a rheostat or variable resistor. When the firing trigger 20is drawn in, the sensor 110 detects the movement, and complete thecircuit used to power the motor 65. When the sensor 110 is a variableresistor or the like, the current supplied to the motor 65, and hencethe output torque of the motor 65, may be generally proportional to theamount of movement of the firing trigger 20. That is, if the operatoronly draws or closes the firing trigger 20 in a little bit, the rotationof the motor 65 is relatively low. When the firing trigger 20 is fullydrawn in (or in the fully closed position), the rotation of the motor 65is at its maximum. In other words, the harder the user pulls on thefiring trigger 20, the more voltage is applied to the motor 65, causinggreater rates of rotation. In other embodiments, the sensor 110 may bean on-off type switch. In such an embodiment, when the firing trigger 20is retracted, the sensor switch 110 is closed, thereby completing thecircuit used to power the motor 65.

The handle 6 may include a middle handle piece 104 adjacent to the upperportion of the firing trigger 20. The handle 6 also may comprise a biasspring 112 connected between posts on the middle handle piece 104 andthe firing trigger 20. The bias spring 112 may bias the firing trigger20 to its fully open position. In that way, when the operator releasesthe firing trigger 20, the bias spring 112 will pull the firing trigger20 to its open position, thereby removing actuation of the sensor 110,thereby stopping rotation of the motor 65. Moreover, by virtue of thebias spring 112, any time a user closes the firing trigger 20, the userwill experience resistance to the closing operation, thereby providingthe user with feedback as to the amount of rotation exerted by the motor65. Further, the operator could stop retracting the firing trigger 20 toremove thereby force from the sensor 100, to stop thereby the motor 65.As such, the user may stop the deployment of the end effector 12,thereby providing a measure of control of the cutting/fasteningoperation to the operator.

The distal end of the helical gear drum 80 includes a distal drive shaft120 that drives a ring gear 122, which mates with a pinion gear 124. Thepinion gear 124 is connected to the main drive shaft 48 of the maindrive shaft assembly. In that way, rotation of the motor 65 causes themain drive shaft assembly to rotate, which causes actuation of the endeffector 12, as described above.

The ring 84 threaded on the helical gear drum 80 may include a post 86that is disposed within a slot 88 of a slotted arm 90. The slotted arm90 has an opening 92 its opposite end 94 that receives a pivot pin 96that is connected between the handle exterior side pieces 59, 60. Thepivot pin 96 is also disposed through an opening 100 in the firingtrigger 20 and an opening 102 in the middle handle piece 104.

In addition, the handle 6 may include a reverse motor (or end-of-strokesensor) 130 and a stop motor (or beginning-of-stroke) sensor 142. Invarious embodiments, the reverse motor sensor 130 may be a limit switchlocated at the distal end of the helical gear drum 80 such that the ring84 threaded on the helical gear drum 80 contacts and trips the reversemotor sensor 130 when the ring 84 reaches the distal end of the helicalgear drum 80. The reverse motor sensor 130 may be part of the circuitused to control the motor 65. When the reverse motor sensor isactivated, the motor control circuit may reverse the direction of themotor 65, thereby withdrawing the knife 32 of the end effector 12following the cutting operation. The stop motor sensor 142 may be, forexample, a normally closed limit switch, and may also be part of themotor control circuit. In various embodiments, it may be located at theproximate end of the helical gear drum 80 so that the ring 84 trips theswitch 142 when the ring 84 reaches the proximate end of the helicalgear drum 80, indicating that the cutting instrument 32 has reached itsproximate (or home or initial) position in the end effector 12.

In operation, when an operator of the instrument 10 pulls back thefiring trigger 20, the sensor 110 detects the deployment of the firingtrigger 20 and the motor control circuit causes the motor 65 to forwardrotate at, for example, a rate proportional to how hard the operatorpulls back the firing trigger 20. The forward rotation of the motor 65in turn causes the ring gear 78 at the distal end of the planetary gearassembly 72 to rotate, thereby causing the helical gear drum 80 torotate, causing the ring 84 threaded on the helical gear drum 80 totravel distally along the helical gear drum 80. The rotation of thehelical gear drum 80 also drives the main drive shaft assembly asdescribed above, which in turn causes deployment of the knife 32 in theend effector 12. That is, the knife 32 and sled 33 are caused totraverse the channel 22 longitudinally, thereby cutting tissue clampedin the end effector 12. Also, the stapling operation of the end effector12 is caused to happen in embodiments where a stapling-type end effectoris used.

By the time the cutting/stapling operation of the end effector 12 iscomplete, the ring 84 on the helical gear drum 80 will have reached thedistal end of the helical gear drum 80, thereby causing the reversemotor sensor 130 to be tripped, which causes the motor control circuitto reverse the direction of the motor 65. This in turn causes the knife32 to retract, and also causes the ring 84 on the helical gear drum 80to move back to the proximate end of the helical gear drum 80.

The middle handle piece 104 includes a backside shoulder 106 thatengages the slotted arm 90 as best shown in FIGS. 8 and 9 . The middlehandle piece 104 also has a forward motion stop 107 that engages thefiring trigger 20. The movement of the slotted arm 90 is controlled, asexplained above, by rotation of the motor 65. When the slotted arm 90rotates CCW as the ring 84 travels from the proximate end of the helicalgear drum 80 to the distal end, the middle handle piece 104 will be freeto rotate CCW. Thus, as the user draws in the firing trigger 20, thefiring trigger 20 will engage the forward motion stop 107 of the middlehandle piece 104, causing the middle handle piece 104 to rotate CCW. Dueto the backside shoulder 106 engaging the slotted arm 90, however, themiddle handle piece 104 will only be able to rotate CCW as far as theslotted arm 90 permits. In that way, if the motor 65 should stoprotating for some reason, the slotted arm 90 will stop rotating, and theuser will not be able to further draw in the firing trigger 20 becausethe middle handle piece 104 will not be free to rotate CCW due to theslotted arm 90.

Components of an exemplary closure system for closing (or clamping) theanvil 24 of the end effector 12 by retracting the closure trigger 18 arealso shown in FIGS. 7-10 . In the illustrated embodiment, the closuresystem includes a yoke 250 connected to the closure trigger 18 by a pin251 that is inserted through aligned openings in both the closuretrigger 18 and the yoke 250. A pivot pin 252, about which the closuretrigger 18 pivots, is inserted through another opening in the closuretrigger 18 which is offset from where the pin 251 is inserted throughthe closure trigger 18. Thus, retraction of the closure trigger 18causes the upper part of the closure trigger 18, to which the yoke 250is attached via the pin 251, to rotate CCW. The distal end of the yoke250 is connected, via a pin 254, to a first closure bracket 256. Thefirst closure bracket 256 connects to a second closure bracket 258.Collectively, the closure brackets 256, 258 define an opening in whichthe proximate end of the proximate closure tube 40 (see FIG. 4 ) isseated and held such that longitudinal movement of the closure brackets256, 258 causes longitudinal motion by the proximate closure tube 40.The instrument 10 also includes a closure rod 260 disposed inside theproximate closure tube 40. The closure rod 260 may include a window 261into which a post 263 on one of the handle exterior pieces, such asexterior lower sidepiece 59 in the illustrated embodiment, is disposedto fixedly connect the closure rod 260 to the handle 6. In that way, theproximate closure tube 40 is capable of moving longitudinally relativeto the closure rod 260. The closure rod 260 may also include a distalcollar 267 that fits into a cavity 269 in proximate spine tube 46 and isretained therein by a cap 271 (see FIG. 4 ).

In operation, when the yoke 250 rotates due to retraction of the closuretrigger 18, the closure brackets 256, 258 cause the proximate closuretube 40 to move distally (i.e., away from the handle end of theinstrument 10), which causes the distal closure tube 42 to movedistally, which causes the anvil 24 to rotate about the pivot point 25into the clamped or closed position. When the closure trigger 18 isunlocked from the locked position, the proximate closure tube 40 iscaused to slide proximately, which causes the distal closure tube 42 toslide proximately, which, by virtue of the tab 27 being inserted in thewindow 45 of the distal closure tube 42, causes the anvil 24 to pivotabout the pivot point 25 into the open or unclamped position. In thatway, by retracting and locking the closure trigger 18, an operator mayclamp tissue between the anvil 24 and channel 22, and may unclamp thetissue following the cutting/stapling operation by unlocking the closuretrigger 20 from the locked position.

Additional configurations for motorized surgical instruments aredisclosed in U.S. Patent Application Publication No. 2007/0175962,entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITHTACTILE POSITION FEEDBACK, now U.S. Pat. No. 7,422,139, which isincorporated herein by reference in its entirety.

FIG. 11 is a schematic diagram of the motor control circuit according tovarious embodiments of the present invention. In various embodiments,the motor control circuit may include one of more integrated circuits(ICs), such as, for example, a processor, memory, microcontroller, timecircuits, etc. In other embodiments, the motor control circuit may notcomprise any ICs. Such a non-IC motor control circuit may beadvantageous because it is often difficult, complicated, and expensiveto sterilize a surgical instrument including ICs.

When an operator initially pulls in the firing trigger 20 after lockingthe closure trigger 18, the sensor 110 is activated (or closed, wherethe sensor 110 is a switch), allowing current to flow therethrough. Ifthe normally open reverse motor sensor switch 130 is open (meaning theend of the end effector stroke has not been reached), current will flowto a single pole, double throw relay 132. When the reverse motor sensorswitch 130 is not closed, a coil 134 of the relay 132 will not beenergized, so the relay 132 will be in its de-energized state.

As shown in FIG. 11 , the circuit may also include a resistive element144 and a switch 146 connected in parallel, with the paralleled elementsconnected in series with the relay 132. The resistive element 144 andthe switch 146 are also connected to the power source 64. The switch 146may be controlled by a control circuit 148 that is responsive to thecutting instrument position sensor 150. According to variousembodiments, the control circuit 148 may open the switch 146 when thecutting instrument 32 is (i) very near to the beginning of its strokeand (ii) very near to the end of its stroke. For example, the controlcircuit may open the switch when the cutting instrument 32 is (i) 0.001inches from the beginning point of its stroke and (ii) 0.001 inches fromthe end of its stroke, as determined by the cutting instrument positionsensor 150. With the switch 146 open, current flows through theresistive element 144, and then through the relay 132, the relay 138,the run motor sensor switch 110, to the motor 65. Current flowingthrough the resistive element 144 reduces the magnitude of the currentdelivered to the motor 65, thereby reducing the power delivered by themotor 65. Thus, when the cutting instrument 32 is (i) very near to thebeginning of its stroke or (ii) very near to the end of its stroke, thepower delivered by the motor 65 is reduced. Conversely, once the cuttinginstrument 32 moves sufficiently far from its beginning point or end ofstroke point, the control circuit 148 may close the switch 146, therebyshorting the resistive element 144, thereby increasing the current tothe motor 65, thereby increasing the power delivered by the motor.

According to various embodiments, the electrical circuit furtherincludes lockout sensor switches 136 a-d collectively defining aninterlock circuit 137 through which current from the relay 132, whende-energized, passes in order for electrical operation of the motor 65to be initiated. Each lockout sensor switch 136 a-d may be configured tomaintain an open (i.e., non-conductive) switch state or a closed (i.e.,conductive) switch state responsive to the presence or absence,respectively, of a corresponding condition. Any of the correspondingconditions, if present when the instrument 10 is fired, may result in anunsatisfactory cutting and stapling operation and/or damage to theinstrument 10. Conditions to which the lockout sensor switches 136 a-dmay respond include, for example, (a) the absence of the staplecartridge 34 in the channel 22, (b) the presence of a spent (e.g.,previously fired) staple cartridge 34 in the channel 22, and (c) an open(or otherwise insufficiently closed) position of the anvil 24 withrespect to the channel 22. Other conditions to which the lockout sensorswitches 136 a-d may respond, such as component wear, may be inferredbased upon an accumulated number of firing operations produced by theinstrument 10. Accordingly, in various embodiments, if any of theseconditions exists, the corresponding lockout sensor switches 136 a-dmaintain an open switch state, thus preventing passage of the currentnecessary to initiate operation of the motor 65. Passage of current bythe lockout sensors 136 a-d is allowed, in various embodiments, onlyafter all of the conditions have been remedied. It will be appreciatedthat the above-described conditions are provided by way of example only,and that additional lockout sensor switches for responding to otherconditions detrimental to operation of the instrument 10 may beprovided. It will similarly be appreciated that for embodiments in whichone or more of the above-described conditions may not exist or are of noconcern, the number of lockout sensor switches may be fewer than thatdepicted.

As shown in FIG. 11 , the lockout sensor switch 136 a may be implementedusing a normally open switch configuration such that a closed switchstate is maintained when the staple cartridge 34 is in a positioncorresponding to its proper receipt by the channel 22. When the staplecartridge 34 is not installed in the channel 22, or is installedimproperly (e.g., mis-aligned), the lockout sensor switch 136 amaintains an open switch state. Lockout sensor switch 136 b may beimplemented using a normally open switch configuration such that aclosed switch state is maintained only when an unspent staple cartridge34 (i.e., a staple cartridge 34 having a sled 33 in the unfiredposition) is present in the channel 22. The presence of a spent staplecartridge 34 in the channel 22 causes the lockout sensor switch 136 b tomaintain an open switch state. Lockout sensor switch 136 c may beimplemented using a normally open switch configuration such that aclosed switch state is maintained when the anvil 24 is in a closedposition with respect to the channel 22. The lockout sensor switch 136 cmay be controlled in accordance with a time delay feature wherein aclosed switch state is maintained only after the anvil 24 is in theclosed position for a pre-determined period of time.

Lockout sensor switch 136 d may be implemented using a normally closedswitch configuration such that a closed switch state is maintained onlywhen an accumulated number of firings produced by the instrument 10 isless than a pre-determined number. The lockout sensor switch 136 d maybe in communication with a counter 139 configured for maintaining acount representative of the accumulated number of firing operationsperformed by the instrument 10, comparing the count to thepre-determined number, and controlling the switch state of the lockoutsensor switch 136 d based upon the comparison. Although shown separatelyin FIG. 11 , it will be appreciated that counter 139 may be integralwith the lockout sensor switch 136 d so as to form a common device.Preferably, the counter 139 is implemented as an electronic devicehaving an input for incrementing the maintained count based upon thetransition of a discrete electrical signal provided thereto. It will beappreciated that a mechanical counter configured for maintaining thecount based upon a mechanical input (e.g., retraction of the firingtrigger 20) may be used instead. When implemented as an electronicdevice, any discrete signal present in the electrical circuit thattransitions once for each firing operation may be utilized for thecounter 139 input. As shown in FIG. 11 , for example, the discreteelectrical signal resulting from actuation of the end-of-stroke sensor130 may be utilized. The counter 139 may control the switch state oflockout sensor switch 136 d such that a closed switch state ismaintained when the maintained count is less than a pre-determinednumber stored within the counter 139. When the maintained count is equalto the pre-determined number, the counter 139 causes the lockout sensorswitch 136 d to maintain an open switch state, thus preventing thepassage of current therethrough. It will be appreciated that thepre-determined number stored by the counter 139 may be selectivelyadjusted as required. According to various embodiments, the counter 304may be in communication with an external display (not shown), such as anLCD display, integral to the instrument 10 for indicating to a usereither the maintained count or the difference between the pre-determinednumber and the maintained count.

According to various embodiments, the interlock circuit 137 may compriseone or more indicators visible to the user of the instrument 10 fordisplaying a status of at least one of the lockout sensor switches 136a-d. More details regarding such indicators may be found in U.S. PatentApplication Publication No. 2007/0175956, entitled ELECTRONIC LOCKOUTSAND SURGICAL INSTRUMENT INCLUDING SAME, now U.S. Pat. No. 7,644,848,which is incorporated herein by reference in its entirety. Thisapplication also includes example mounting arrangements andconfigurations for the lockout sensor switches 136 a-d.

In the illustrated embodiment, when the lockout sensor switches 136 a-dcollectively maintain a closed switch state, a single pole, single throwrelay 138 is energized. When the relay 138 is energized, current flowsthrough the relay 138, through the run motor switch sensor 110, and tothe motor 65 via a double pole, double throw relay 140, thereby poweringthe motor 65, allowing it to rotate in the forward direction. Accordingto various embodiments, because the output of the relay 138, onceenergized, maintains the relay 138 in an energized state until relay 132is energized, the interlock circuit 137 will not function to preventoperation of the motor 165 once initiated, even if one or more of theinterlock sensor switches 136 a-d subsequently maintains an open switchstate. In other embodiments, however, it may be necessary or otherwisedesirable to connect the interlock circuit 137 and the relay 138 suchthat one or more the lockout sensor switches 136 a-d must maintain aclosed switch state in order to sustain operation of the motor 165 onceinitiated.

Rotation of the motor in the forward direction causes the ring 84 tomove distally and thereby de-actuate the stop motor sensor switch 142 invarious embodiments. Because the switch 142 is normally closed, asolenoid 141 connected to the switch 142 may be energized. The solenoid141 may be a conventional push-type solenoid that, when energized,causes a plunger (not shown) to be axially extended. Extension of theplunger may operate to retain the closure trigger 18 in the retractedposition, thus preventing the anvil 24 from opening while a firingoperation is in progress (i.e., while the switch 142 is not actuated).Upon de-energization of the solenoid 141, the plunger is retracted suchthat manual release of the closure trigger 18 is possible.

When the end effector 12 reaches the end of its stroke, the reversemotor sensor 130 will be activated, thereby closing the switch 130 andenergizing the relay 132. This causes the relay 132 to assume itsenergized state (not shown in FIG. 11 ), which causes current to bypassthe interlock circuit 137 and run motor sensor switch 110, and insteadcauses current to flow to both the normally-closed double pole, doublethrow relay 140 and back to the motor 65, but in a manner, via the relay140, that causes the motor 65 to reverse its rotational direction.Because the stop motor sensor switch 142 is normally closed, currentwill flow back to the relay 132 to keep it energized until the switch142 opens. When the knife 32 is fully retracted, the stop motor sensorswitch 142 is activated, causing the switch 142 to open, therebyremoving power from the motor 65, and de-energizing the solenoid 141.

FIG. 12 illustrates a timeline of the operation of the circuit accordingto various embodiments Assuming the lockout switches 136 a-d are intheir appropriate state, at time T0 the operator retracts the firingtrigger 20, closing the run motor sensor switch 110, causing the motor65 to forward rotate. At this time, the switch 146 is open, so currentflows through the resistive element 144, reducing the current to themotor 65 from time T0 to time T1. At time T1, which the cuttinginstrument is sufficiently far from its initial position, the switch 146is closed, thereby shorting the resistive element 144 and supplyingincreased power to the motor 65. From time T1 to time T2, the motor isin its full power mode with the switch 146 closed. At time T2, as thecutting instrument 32 gets near to the end of its stroke, the switch 146is opened, thereby reducing the current supplied to the motor 65. Thus,from T2 to T3 the motor 65 is at less than full power.

At time T3, the end-of-stroke sensor switch 130 is closed, causing themotor 65 to reverse rotate. The motor 65 is still in its reduced powerstate because switch 146 is opened, and the motor 65 remains in itsreduced power state until time T4, when the switch 146 is closed becausethe cutting instrument 32 has moved sufficiently far from itsend-of-stroke position. From time T4 to T5 the motor 65 operates at fullpower retracting the cutting instrument 32. At time T5, as the cuttinginstrument 32 gets near to its initial (or stop) position, the switch146 again opens, thereby limiting current to the power 65, therebyreducing the power delivered by the motor 65. At time T6, the stop motorsensor switch 142 is opened, thereby removing current from the motor,causing it to stop rotating.

In such a switching architecture, the motor-driven instrument 10exhibits a “soft” start quality by limiting the motor's ability to exertfull load immediately. The motor 65 is initially in a reduced power mode(from time T0 to time T1), so as to limit the sudden jerking start. Inaddition, by starting the soft start mode, the likelihood of the motoroverpowering the cartridge lockout mechanism is reduced. In addition,reducing the power prior to the knife reaching its end-of-stroke (ordistal) position eases reversal of the motor direction.

In other embodiments, the parallel-connected switch 146 and resistiveelement 144 are connected in different places, but preferably they arealways in the current loop regardless of whether the motor 65 is beingforward rotated or reverse rotated. In addition, the resistive element144 may be any type of circuit element or electrical component thatprovides sufficient resistance. For example, the resistive element 144could be one or a number of parallel-connected resistors.

In addition, the resistive element 144 may comprise a variable resistor,as shown in FIG. 13 . In such an embodiment, the switch 146 may or maynot be used. FIG. 13 shows an embodiment without the switch 146. Thecontrol circuit 148 may vary the resistance of the variable resistiveelement 144 based on the position of the cutting instrument 32, forexample. That way, instead of having two power levels for the motor 65,there could be a number of discrete power levels or a continuous rangeof power levels for the motor 65, depending on the nature of thevariable resistive element 144. In various embodiments, the variableresistive element may comprise a string potentiometer or cable positiontransducer, where, for example, the resistance is related to theposition of the knife 32 in the end effector 12. In addition, an activeelement, such as a transistor, could be used to provide a variableresistance. For example, FIG. 14 illustrates a circuit where a FET 147is used as a variable resistor to limit the current to the motor 65 invarious operational states.

In yet other embodiments, an integrated switch mode controller, such asthe UC2637 from Texas Instrument or some other suitable motor drivecircuit, could be used to limit the torque and/or speed of the motor 65at various times during the cutting stroke cycle, such as a “soft”start, within the lockout region, prior to stopping or reversingdirection, etc. According to yet other embodiments, as shown in FIG. 15, a pulse width modulation circuit 148 may be used to control the speedof the motor 65 by driving the motor with short pulses. The duration ofthe pulses may be varied to control the speed of the motor 65; thelonger the pulses, the faster the motor turns, and vice versa.Accordingly, short duration pulses may be used when the cuttinginstrument 32 is initially leaving or returning to its initial position,or approaching or leaving its end-of-stroke position, etc. In addition,in yet other embodiments, a frequency modulation circuit 149, as shownin FIG. 16 , may be used to control the speed of the motor 65. In afrequency modulation circuit, the duty cycle of the pulse remainsconstant, but the frequency of the pulses changes to vary the speed ofthe motor. Accordingly, low frequency pulses may be used when thecutting instrument 32 is initially leaving or returning to its initialposition, or approaching or leaving its end-of-stroke position, etc.,and high frequency pulses may be used when greater motor speed isrequired.

In yet other embodiments, an amplifier circuit 151 may be used tocontrol the speed of the motor 65, as shown in FIG. 17 . The amplifiercircuit 151 may amplify, for example, the current or voltage applied tothe motor 65. According to various embodiments, the amplifier circuit151 may comprise a Darlington transistor pair or some other suitabletransistor-based amplifier circuit.

In other embodiments, rather than an on-off type run motor sensor switch110, a proportional-type variable resistor sensor could be used instead.In such embodiments, the rate of rotation of the motor 65 would beproportional to the force applied by the operator. The run-motor sensor110 may provide an open circuit resistance when the firing trigger 20 isnot retracted/actuated, and then provide a decreasing resistance as thefiring trigger is retracted. Whether the switch 110 comprises an on-offtype switch or a variable resistor, if the operator releases the firingtrigger 20 during a procedure while the motor is in the forwarddirection, power to the motor 65 will be eliminated or at least reduced,thereby providing a dynamic braking feature for the instrument 10.

In other embodiments, as shown in FIG. 18 , the switches 140 a and 140 bmay be actively controlled, rather than through the relay 140 shown inFIG. 11 , for example. In such embodiments, just before the end of thestroke is sensed, one of the switches 140 a, 140 b may switch polarityso that both switches 140 a, 140 b are connected to the same polarityterminal for the motor 65 (e.g., either both positive or both negative).This will remove power from the motor 65, causing it to stop. FIG. 18shows an embodiment where the switches 104 a and 140 b are bothconnected to the positive terminal. Then, at about the same time theend-of stroke is sensed or soon thereafter, the other switch 140 a, 140b may switch polarity, allowing the motor 65 to rotate in the reversedirection. In the example of FIG. 18 , this may be done by switchingswitch 140 a to the negative terminal. Of course, in other embodiments,the switch 140 a could be first switched to the negative terminal andthen the switch 140 b could be switched to the positive terminal. Also,other switching arrangements could be used to temporarily remove powerfrom the motor 65 prior to it switching direction to provide such“active braking.” For example, the switches 140 a, 140 b may still becontrolled by an inductive relay, and the circuit may include anotherswitching circuit for actively braking the motor 65.

The active braking could be combined with variable power levels suppliedto the motor 65 as described above in connection with FIGS. 11 and 12 ,for example. FIG. 19 shows a timing diagram that incorporates activebraking. At time T2.1, between times T2 and T3, the power may be removedfrom the motor 65 by switching one of the switches 140 a, 104 b, forexample, thereby braking the motor. Then at time T3, the end-of-strokeswitch 130 may be closed and the other switch 140 a, 140 b may beswitched to supply power to the motor 65, but in the reverse direction,as described above.

The control circuit 135 or some other control circuit may control theswitching of the switches 140 a, 140 b. According to variousembodiments, the control circuit 135 may comprise a processor andmemory. For example, the control circuit 135 may comprise an IC-basedmicrocontroller. The memory may store data indicative of the type ofcartridge 34 loaded in the end effector 12. For example, the memory maystore data indicative of the length of the cut needed for the cartridge34. Based on this data, the control circuit 135 can control when theswitches 146, 140 a, and 140 b switch. As the cartridges 34 are oftenreplaceable in certain types of instruments 10, the identifying data maybe transmitted to the control circuit 135 by a RFID tag or transponderconnected to or associated with the cartridge 34 or by some other means.The RFID signal from the tag may be received by the control circuit 135and stored in memory. In other embodiments, a transponder associatedwith the cartridge 34 may send identifying data to the control circuit135 via one or more inductive links, such as described in U.S. PatentApplication Publication No. 2008/0167522, entitled SURGICAL INSTRUMENTWITH WIRELESS COMMUNICATION BETWEEN CONTROL UNIT AND SENSORTRANSPONDERS, now U.S. Pat. No. 8,652,120, which is incorporated hereinby reference in its entirety.

According to other embodiments, the control circuit 135 may not containany integrated circuits. For example, the control circuit 135 maycomprise analog timer circuits (e.g., RC-based timer circuits) forcontrolling the switch timing of the switches 146, 140 a-b. According tosuch an embodiment, the control circuit 135 may receive informationabout the length of the cut for the particular cartridge 34 being usedbased on the completion of an electrical circuit when the cartridge 34is inserted into the channel 22. For example, as shown in FIG. 20 , thechannel 22 may comprise a number of contact pads 220 positioned to facethe lower surface of the cartridge 34 when the cartridge 34 is loaded inthe channel 22. The lower surface of the cartridge 34 also may comprisea number of contacts 222, as shown in FIG. 21 . The number andpositioning of the contacts 222 on the cartridge 34 may identify thetype of cartridge. For example, the number and positioning of thecontacts 222 may identify the cut length for the cartridge 34. Allcartridges of the same cut length would preferably have the same contactpattern; cartridges with different cut lengths would have differentcontact patterns. The circuit completed when the contacts 222 of thecartridge 34 contact the contacts 220 of the channel 22 may have anumber of different resistors, a subset of which are connected in thecompleted circuit when the contacts 222 of the cartridge 34 contact thecontacts 220 of the channel 22. Depending on the contact pattern on thecartridge 34, different resistors may be in the completed circuit. Theresistors may be connected to the control circuit 135, and may be usedin the RC circuits to generate the timing signals for the switches 146,140 a, 140 b. That way, the control circuit 135 can control the switches146, 140 a-b based on the type of cartridge 34 loaded in the endeffector 12.

In another embodiment, the lower surface of the cartridge 34 maycomprise a plunger 230, as shown in FIG. 22 . The channel 22 maycomprise a number of switches 232, as shown in FIG. 23 , one of which isactuated by the plunger 230 when the cartridge 34 is loaded in the endeffector 12. The switch 232 may have a different associated resistorcircuit. Each of the resistor circuits may be connected to the controlcircuit 135, but only one would be activated when the cartridge 34 isloaded in the channel 22, depending on the location of the plunger 230.Each replaceable cartridge 34 having the same cut length preferablywould have the plunger 230 in the same position. Cartridges 34 withdifferent lengths would preferably have plungers 230 in differentpositions. Because the end effector 12 may only accommodate a finitenumber of different cartridges (e.g., 5), the channel 22 would only needa corresponding number of switches 232 and there would only be acorresponding number of acceptable plunger locations.

In other embodiments, the instrument 10 may comprise an externalselector 240, such as dip switch or other suitable input device, wherebyan operator of the instrument or other person could input identifyingdata for the cartridge 34 being used. As shown in FIG. 24 , the handlemay comprise such a selector 240 for embodiments where the controlcircuit 135 comprises an IC or embodiments where the control circuit 135does not comprise any ICs.

FIG. 25 shows another embodiment of the motor circuit. When the runmotor (or fire) switch 110 is closed (it is shown in an open state inFIG. 25 ), when the safety switch 240 is closed (it is shown open inFIG. 25 ) indicating that the device safety is set, and when thenormally-closed lockout switch 242 it opened indicating that theinstrument is not in a lock-out condition, current flows through thesafety switch 240, through the lockout indicator 244 (which may be a LEDas shown in FIG. 25 ) to the motor 65. When the end of the cuttingstroke is reached, the end-of-stroke or direction switch 130 isswitched, reversing the direction of the motor 65 (with the fire switch110 also having been released). In this state, current also flowsthrough a reverse direction indicator 246, such as an LED, providing avisual indication that the motor direction has been reversed.

As shown in FIG. 25 , the circuit may also comprise a manual returnswitch 248. The operator may manually flip this switch if the cuttinginstrument 32 has only been partially fired. Switching the manual returnswitch 248 causes the motor 65 to reverse rotate, causing the cuttinginstrument 32 to return to its original or home position.

The battery 64 of the instrument 10 may comprise one or moreseries-connected battery cells. In various embodiments, a cell selectionswitch may control how many of the battery cells are being used to powerthe motor 65 at a given time to control the power available to the motor65. This would allow the operator of the instrument to have greatercontrol over both the speed and the power of the motor 65. In anotherembodiment, the instrument may comprise a power regulator, including,for example, a DC-to-DC converter, that regulates the voltage suppliedto the motor. Further, the voltage set point for the power regulatorcould be set so that the voltage delivered from the power source is lessthan the voltage at which the power source delivers maximum power. Thatway, the power source (e.g., a number of series-connected battery cells)could operate on the “left” or increasing side of the power curve, sothat increases in power would be available.

In addition, according to various embodiments, the power source 64 maycomprise secondary accumulator devices, such as rechargeable batteriesor supercapacitors. Such secondary accumulator devices may be chargedrepeatedly by replaceable batteries. A charge management circuit maycontrol the charging of the secondary accumulator devices and providevarious status signals, such as an alert, when the charging of thesecondary accumulator devices is complete.

In other embodiments, the power source or power pack comprising thesecondary accumulator devices may be removable from the instrument andconnectable to a remote charger base. The charger base may charge thesecondary accumulator devices, such as from the AC electrical mains or abattery. The charger base may also comprise a processor and memory unit.Data stored in a memory of the removable power pack may be downloaded tothe charger base, from which it may be uploaded for later use andanalysis, such as by the user (e.g., physician), the manufacturer, ordistributor of the instrument, etc. The data may comprise operatingparameters, such as charge cycle information, as well as ID values forvarious replaceable components of the instrument, such as the staplecartridge.

More details regarding such power sources may be found in commonlyassigned U.S. patent application Ser. No. 12/031,556, entitled MOTORIZEDSURGICAL CUTTING AND FASTENING INSTRUMENT, now U.S. Pat. No. 8,636,736,and Ser. No. 12/031,567, entitled MOTORIZED SURGICAL CUTTING ANDFASTENING INSTRUMENT HAVING HANDLE BASED POWER SOURCE, now U.S. Pat. No.8,657,174, both of which were filed on Feb. 14, 2008, and both of whichare incorporated herein by reference in their entirety.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Preferably, the various embodiments of the invention described hereinwill be processed before surgery. First, a new or used instrument isobtained and if necessary cleaned. The instrument can then besterilized. In one sterilization technique, the instrument is placed ina closed and sealed container, such as a thermoformed plastic shellcovered with a sheet of TYVEK. The container and instrument are thenplaced in a field of radiation that can penetrate the container, such asgamma radiation, x-rays, or high-energy electrons. The radiation killsbacteria on the instrument and in the container. The sterilizedinstrument can then be stored in the sterile container. The sealedcontainer keeps the instrument sterile until it is opened in the medicalfacility.

It is preferred that the device is sterilized. This can be done by anynumber of ways known to those skilled in the art including beta or gammaradiation, ethylene oxide, steam and other methods.

While the present invention has been illustrated by description ofseveral embodiments and while the illustrative embodiments have beendescribed in considerable detail, it is not the intention of theapplicant to restrict or in any way limit the scope of the appendedclaims to such detail. Additional advantages and modifications mayreadily appear to those skilled in the art. The various embodiments ofthe present invention represent vast improvements over prior staplemethods that require the use of different sizes of staples in a singlecartridge to achieve staples that have differing formed (final) heights.

Accordingly, the present invention has been discussed in terms ofendoscopic procedures and apparatus. However, use herein of terms suchas “endoscopic” should not be construed to limit the present inventionto a surgical stapling and severing instrument for use only inconjunction with an endoscopic tube (i.e., trocar). On the contrary, itis believed that the present invention may find use in any procedurewhere access is limited, including but not limited to laparoscopicprocedures, as well as open procedures. Moreover, the unique and novelaspects of the various staple cartridge embodiments of the presentinvention may find utility when used in connection with other forms ofstapling apparatuses without departing from the spirit and scope of thepresent invention.

What is claimed is:
 1. A surgical system, comprising: an end effector,comprising: a first jaw; and a second jaw rotatable relative to saidfirst jaw between an open position and a closed position; a firingmember movable within said end effector along a firing path between astarting position and an ending position; a motor comprising a shaft,wherein said motor is configured to drive said firing member toward saidending position based on said shaft rotating in a first rotationaldirection; a battery pack operably coupled with said motor, wherein saidbattery pack comprises at least two battery cells, wherein said at leasttwo battery cells are connected in series as said firing member movesbetween said starting position and said ending position, and whereinsaid battery pack is configured a provide a set voltage to said motorduring the operation thereof; and a control circuit operably coupled tosaid motor, wherein said control circuit is configured to switch betweena plurality of operational modes during said rotation of said shaft insaid first rotational direction, and wherein said plurality ofoperational modes comprises: a first operational mode, wherein a firstamount of current is supplied to said motor from said battery pack, andwherein said control circuit operates in said first operational mode assaid firing member is driven from said starting position toward apredetermined position along said firing path; and a second operationalmode, wherein a second amount of current is supplied to said motor fromsaid battery pack, wherein said second amount of current is greater thansaid first amount of current, and wherein said control circuit operatesin said second operational mode as said firing member is driven fromsaid predetermined position toward said ending position; wherein saidcontrol circuit comprises a power control switch configurable between afirst state and a second state, wherein said control circuit is in saidfirst operational mode based on said power control switch being in saidfirst state, and wherein said control circuit is in said secondoperational mode based on said power control switch being in said secondstate; wherein said surgical system further comprises a position sensorconfigured to sense a position of said firing member, wherein said powercontrol switch is configured to transition towards said second statebased on said position sensor sensing said firing member reaching saidpredetermined position.
 2. The surgical system of claim 1, wherein saidpredetermined position is a first predetermined position, wherein saidfiring path comprises a second predetermined position positioned betweensaid first predetermined position and said ending position, and whereinsaid power control switch is configured to transition towards said firststate based on said position sensor sensing said firing member reachingsaid second predetermined position.
 3. The surgical system of claim 1,wherein said control circuit further comprises an end-of-stroke switchconfigurable between an activated state and a deactivated state, andwherein said end-of-stroke switch is configured to transition towardssaid activated state based on said position sensor sensing said firingmember reaching said ending position.
 4. The surgical system of claim 3,wherein said motor is configured to rotate said shaft in a secondrotational direction to drive said firing member toward said startingposition based on said end-of-stroke switch being in said activatedstate.
 5. The surgical system of claim 1, wherein said control circuitfurther comprises a lockout switch, and wherein said lockout switch isconfigured to prevent said battery pack from providing power to saidmotor absent said second jaw being in said closed position.
 6. Thesurgical system of claim 1, wherein said end effector further comprisesa staple cartridge.
 7. A surgical system, comprising: an end effector,comprising: a first jaw; and a second jaw rotatable relative to saidfirst jaw between an open position and a closed position; a firingmember movable within said end effector along a firing path between astarting position and an ending position; a motor comprising a shaft,wherein said motor is configured to drive said firing member toward saidending position based on said shaft rotating in a first rotationaldirection; a battery pack operably coupled with said motor, wherein saidbattery pack comprises at least two battery cells, wherein said at leasttwo battery cells are connected in series as said firing member movesbetween said starting position and said ending position, and whereinsaid battery pack is configured a provide a set voltage to said motorduring the operation thereof; and a control circuit operably coupled tosaid motor, wherein said control circuit is configured to switch betweena plurality of operational modes during said rotation of said shaft insaid first rotational direction, and wherein said plurality ofoperational modes comprises: a first operational mode, wherein a firstamount of current is supplied to said motor from said battery pack, andwherein said control circuit operates in said first operational mode assaid firing member is driven from said starting position toward apredetermined position along said firing path; and a second operationalmode, wherein a second amount of current is supplied to said motor fromsaid battery pack, wherein said second amount of current is greater thansaid first amount of current, and wherein said control circuit operatesin said second operational mode as said firing member is driven fromsaid predetermined position toward said ending position; wherein saidcontrol circuit comprises a power control switch configurable between afirst state and a second state, wherein said control circuit is in saidfirst operational mode based on said power control switch being in saidfirst state, and wherein said control circuit is in said secondoperational mode based on said power control switch being in said secondstate; wherein said control circuit further comprises a resistor,wherein current from said battery pack is configured to flow throughsaid resistor based on said power control switch being in said firststate, and wherein current from said battery pack bypasses said resistorbased on said power control switch being in said second state.
 8. Thesurgical system of claim 7, wherein said control circuit furthercomprises a lockout switch, and wherein said lockout switch isconfigured to prevent said battery pack from providing power to saidmotor absent said second jaw being in said closed position.
 9. Thesurgical system of claim 7, wherein said end effector further comprisesa staple cartridge.
 10. A surgical system, comprising: an end effector,comprising: a first jaw; and a second jaw movable relative to said firstjaw between an open position and a clamped position; a firing membermovable within said end effector along a firing path between a proximalposition and a distal position; a motorized system configured to drivesaid firing member between said proximal position and said distalposition; a power pack operably coupled with said motorized system,wherein said power pack comprises at least two power cells, wherein saidat least two power cells are connected in series as said firing membermoves between said proximal position and said distal position, andwherein said power pack is configured to provide a substantiallyconstant voltage to said motorized system during the operation thereof;and a control circuit operably coupled to said motorized system, whereinsaid control circuit is configured to switch between a plurality ofoperational configurations as said motorized system drives said firingmember toward said distal position, and wherein said plurality ofoperational configurations comprises: a first operational configuration,wherein a first amount of current is supplied to said motorized systemfrom said power pack, and wherein said control circuit is in said firstoperational configuration as said firing member is driven from saidproximal position toward a predetermined position along said firingpath; and a second operational configuration, wherein a second amount ofcurrent is supplied to said motorized system from said power pack,wherein said second amount of current is greater than said first amountof current, and wherein said control circuit is in said secondoperational configuration as said firing member is driven from saidpredetermined position toward said distal position; wherein said controlcircuit comprises a power control switch configurable between a firststate and a second state, wherein said control circuit is in said firstoperational configuration based on said power control switch being insaid first state, and wherein said control circuit is in said secondoperational configuration based on said power control switch being insaid second state; wherein said surgical system further comprises aposition sensor configured to sense a position of said firing member,wherein said power control switch is configured to transition towardssaid second state based on said position sensor sensing said firingmember reaching said predetermined position.
 11. The surgical system ofclaim 10, wherein said predetermined position is a first predeterminedposition, wherein said firing path comprises a second predeterminedposition positioned between said first predetermined position and saiddistal position, and wherein said power control switch is configured totransition towards said first state based on said position sensorsensing said firing member reaching said second predetermined position.12. The surgical system of claim 10, wherein said control circuitfurther comprises an end-of-stroke switch configurable between anactivated state and a deactivated state, and wherein said end-of-strokeswitch is configured to transition towards said activated state based onsaid position sensor sensing said firing member reaching said distalposition.
 13. The surgical system of claim 12, wherein said motorizedsystem is configured to drive said firing member toward said proximalposition based on said end-of-stroke switch being in said activatedstate.
 14. The surgical system of claim 10, wherein said control circuitfurther comprises a lockout switch, and wherein said lockout switch isconfigured to prevent said power pack from providing power to saidmotorized system absent said second jaw being in said clamped position.15. The surgical system of claim 10, wherein said end effector furthercomprises a staple cartridge.
 16. A surgical system, comprising: an endeffector, comprising: a first jaw; and a second jaw movable relative tosaid first jaw between an open position and a clamped position; a firingmember movable within said end effector along a firing path between aproximal position and a distal position; a motorized system configuredto drive said firing member between said proximal position and saiddistal position; a power pack operably coupled with said motorizedsystem, wherein said power pack comprises at least two power cells,wherein said at least two power cells are connected in series as saidfiring member moves between said proximal position and said distalposition, and wherein said power pack is configured to provide asubstantially constant voltage to said motorized system during theoperation thereof; and a control circuit operably coupled to saidmotorized system, wherein said control circuit is configured to switchbetween a plurality of operational configurations as said motorizedsystem drives said firing member toward said distal position, andwherein said plurality of operational configurations comprises: a firstoperational configuration, wherein a first amount of current is suppliedto said motorized system from said power pack, and wherein said controlcircuit is in said first operational configuration as said firing memberis driven from said proximal position toward a predetermined positionalong said firing path; and a second operational configuration, whereina second amount of current is supplied to said motorized system fromsaid power pack, wherein said second amount of current is greater thansaid first amount of current, and wherein said control circuit is insaid second operational configuration as said firing member is drivenfrom said predetermined position toward said distal position; whereinsaid control circuit comprises a power control switch configurablebetween a first state and a second state, wherein said control circuitis in said first operational configuration based on said power controlswitch being in said first state, and wherein said control circuit is insaid second operational configuration based on said power control switchbeing in said second state; wherein said control circuit furthercomprises a resistor, wherein current from said power pack is configuredto flow through said resistor based on said power control switch beingin said first state, and wherein current from said power pack bypassessaid resistor based on said power control switch being in said secondstate.
 17. The surgical system of claim 16, wherein said control circuitfurther comprises a lockout switch, and wherein said lockout switch isconfigured to prevent said power pack from providing power to saidmotorized system absent said second jaw being in said clamped position.18. The surgical system of claim 16, wherein said end effector furthercomprises a staple cartridge.
 19. A surgical system, comprising: an endeffector, comprising: an anvil; and an elongate channel, wherein saidanvil and said elongate channel are configurable between an openconfiguration and a closed configuration; a firing member movable withinsaid end effector along a firing path between a starting position and anending position; a motor configured to drive said firing member towardsaid ending position; a battery pack operably coupled with said motor,wherein said battery pack comprises at least two battery cells, andwherein said at least two battery cells are connected in series as saidfiring member moves between said starting position and said endingposition; and a control circuit operably coupled to said motor, whereinsaid control circuit is configured to switch between a plurality ofoperational states as said motor drives said firing member toward saidending position, and wherein said plurality of operational statescomprises: a first operational state, wherein a first amount of currentis supplied to said motor from said battery pack, and wherein saidcontrol circuit operates in said first operational state as said firingmember is driven from said starting position toward a predeterminedposition along said firing path; and a second operational state, whereina second amount of current is supplied to said motor from said batterypack, wherein said second amount of current is greater than said firstamount of current, wherein said control circuit operates in said secondoperational state as said firing member is driven from saidpredetermined position toward said ending position, and wherein avoltage provided to said motor from said battery pack is substantiallythe same in said first operational state and said second operationalstate.
 20. The surgical system of claim 19, further comprising a staplecartridge removably positioned in said elongate channel.
 21. A surgicalsystem, comprising: an end effector, comprising: an anvil; and anelongate channel, wherein said anvil and said elongate channel areconfigurable between an open configuration and a closed configuration; afiring member movable within said end effector along a firing pathbetween a starting position and an ending position; a motor configuredto drive said firing member toward said ending position; a battery packoperably coupled with said motor, wherein said battery pack comprises atleast two battery cells, and wherein said at least two battery cells areconnected in series as said firing member moves between said startingposition and said ending position; and a control circuit operablycoupled to said motor, wherein said control circuit is configured toswitch between a plurality of operational states as said motor drivessaid firing member toward said ending position, and wherein saidplurality of operational states comprises: a first operational state,wherein a first amount of current is supplied to said motor from saidbattery pack, and wherein said control circuit operates in said firstoperational state as said firing member is driven from said startingposition toward a predetermined position along said firing path; and asecond operational state, wherein a second amount of current is suppliedto said motor from said battery pack, wherein said second amount ofcurrent is greater than said first amount of current, wherein saidcontrol circuit operates in said second operational state as said firingmember is driven from said predetermined position toward said endingposition, and wherein a voltage supplied to said motor from said batterypack in said second operational state comprises an unadjusted voltagerelative to a voltage supplied to said motor from said battery pack insaid first operation state.